Cladistics and Eclecticism
tdib at OCEANCONSERVANCY.ORG
Fri Feb 8 11:00:18 CST 2002
From: SKÁLA Zdenek
Yes, characters are used for cladogram construction. Quite surprisingly to
me, you are considering them as irrelevant immediately after the cladogram
But why do you say that? Character information is presented along with the
cladogram, giving us a framework around which to understand the evoltution
of characters. I think this is an immensly valuable contribution, and can
hardly be considered as deeming characters irrelevant.
What we really do in cladogram construction is summarizing the "amount of
character change" (i.e. the largest clusters of mutually compatible
synapomorphies) to construct/recognize "real" clades.
No, I don' think that that is the goal. It is true that we use the number of
synapomorphies at particular nodes to adjudicate the "weight of evidence"
when there is character conflict. But the focused goal is arrive at a deeper
understanding of characters - which similar character states are really the
same thing - historically - i.e. homologies, and which ones are similar by
convergence. I think this is crucial and fundamental research in any effort
to understand characters.
Eclecticists simply take this operation seriously and use these clusters of
synapomorphies also for the splitting of the cladogram.
Yeah, but that destroys the ability of the cladogram splits to represent the
history of lineage splits. In other words, that defeats the whole purpose of
using systematics in the pursuit of understanding the history of life.
Well, mono(holo)phyletic taxa need not be arbitrary (in the sense of
cladogram split) if you will recognize all clades as taxa.
Yes, that is the point.
With this method (which you apparently acknowledge as possible) even most of
cladists will disagree, IMO. Otherwise, there is still the same amount of
arbitrariness in the splitting of the cladogram into taxa - be it
holophyletic or paraphyletic.
OK, I think we agree. So long as we recognize all clades as taxa, we are not
as arbitrary as ecleticists, - is that what you are saying? I can agree with
this. I think that the discovery of a clade and the recognition of a taxon
is the same thing.
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